In recent years, high-performance digital complex machines have been commercialized and it has become easy to copy a work such as a book, in an almost identical form to its original work by forming an image of the work. Further, with the widespread of the Internet in these years, it has become possible to deliver image data, read out from a book or the like, to an unspecified number of users.
However, many cases concerning damage of works have occurred including a case where the copyrighted book or the like is presented in the form of image data and distributed without permission of the author. In order to prevent such unauthorized distribution of image data, for example, a technique disclosed in Patent Document 1 (Japanese Unexamined Patent Publication No. 62870/2004 (Tokukai 2004-62870, publication date: Feb. 26, 2004)) has been proposed.
Specifically, in a system disclosed in Patent Document 1, in regard to data of a work desired by a user, when a criterion allowing for use of the data is provided with a server storing the data and when the server allows for the use based on the criterion, a user can receive the data of the work from the server. This allows for private use of the data, while preventing unauthorized copying. The system allows for copying of a work in the form of data only for private use.
On the other hand, for example, Patent Document 2 (Japanese Unexamined Patent Publication No. 164551/2004 (Tokukai 2004-164551, publication date: Jun. 10, 2004)) discloses a technique for preventing unauthorized copying using a copy machine with regard to a physical work such as a book.
Patent Document 2 describes a book to which a storage medium such as an IC tag or the like is added. In the book, information concerning whether to permit reading of the book is stored beforehand, so that reading of the book is controlled based on the information.
However, such a conventional arrangement has such a problem that the book is copied without limitation after the storage medium is removed.
Specifically, in Patent Document 2, information concerning whether to permit reading of the book is stored beforehand in the storage medium added to the book. Then, based on the information, a determination is made as to whether to carry out reading of the book. However, in Patent Document 2, after the removal of the storage medium added to the book, there will be no information concerning whether to permit reading of the book, with the result that the book is read without limitation. This eventually allows unlimited copying of the book.